Grit reclamation method



2 Sheets-Sheet l W. L. JOHNSON ETAI- GRIT RECLAMATION METHOD Oct. 11,1966 Original Filed May 25, 1961 UUMLJJLIM Oct. 11, 1966 w. L JOHNSON ETAL GRIT RECLAMATION METHOD 2 Sheets-Shale?l 2 Original Filed May 23,1961 INVENTORS. Raaf/er 6. Mu/sn? wc/vous z /wvz/m Manko Jaw/v60# UnitedStates Patent Oiiice 3,278,027 Patented Oct. 11, 1966 This applicationis a divisional of our pending application Serial No. 125,609, filed May23, 1961, now Patent No. 3,122,863, dated March 3, 1964.

This invention relates to methods for separating unwanted tineparticles, dirt, etc. and excess liquids from suspension carryingparticulate solids, and to the processes of such separation.

More particularly, this invention relates to deburring and abradingapparatus and processes of the type wherein smoothing, trimming, or, ingeneral, surface reforming of manufactured parts is effected by hardparticles entrained in high velocity liquid streams. Apparatus of thisgeneral type for deburring, peening and/or abrading is shown, forexample, in the copending Emil Umbricht et al. patent application US.Serial No. 9,910 tiled on now Patent No. 3,150,467, dated sake ofAbrevity we shall refer to such hard particles, whether sharp abrasivegrains or smooth shot or smaller particles, etc., `for surface reformingby the term grit As fully described in our coworkers above-identifiedPatent No. 3,150,467, the grit is suspended in a liquid medium containedin a hopper-like tank, or sump, veniently positioned. The gritgravitates toward the botaccelerated upward through a blast tube,extending to the surface iof the liquid mass and is directed into ablasting chamber and against the manufactured part positioned therein.

Because high pressure liquid jets are used to drive the grit against thesurfaces being treated, and for washing away residual grit from theparts and the apparatus, it is necessary to separate excess yliquidbefore re-using the grit. Moreover, since the treatment with the gritknocks and scrapes off from the treated parts small pieces and particlesof metal, mold or core sand, scale, dirt, etc., which drain back fromthe Also slimes, oils, colloidal particles, detergents and surfacecoating materials of various kinds parts during treatment and grit whichis desired for re-use.

It is, `of course, desirable to collect the drain-back directly as itfalls from the part being treated and the chamber around it; but sincewashing and separation of the grit are necessary, the recovered materialhas had to be taken oif for such treatment. When the grit used isabrasive, every transfer of this kind which requires pumping or rapidmovement is a source of deterioration of the apparatus and the grit.

The present invention is concerned with improving the method forreclaiming and returning the grit for re-use. It is particularlyconcerned with a method for separating, reconditioning and returning thegrit, which will be so etlicient and compact that those functions can beaccomplished in the zone beneath'the blasting zone.

With this object in view, we provide a liquid-return system having asump, sloping surfaces leading t-o the sump, and weit edges, all locatedto collect the drainthe entraining liquid, the grit, and The drain-backinto the sump creates control the conditions of the overflow aseparation of wast-e matter, with superfluous liquid, from the grit anda part of the liquid, which are retained in the sump and re-used. Tothis end we provide a level weir edge around the sump, of such length asto limit the depth and velocity of the overow. Thus we carry off the nerdirt and waste. Advantageously, we also provide bales adjacent to theback material, i.e., superfluous matter. an overiiow; and we So that iteffects less readily suspended solids remain to settle in the sump andserve as surface reforming grains for further operation of the process.

Because of its more rapid settling rate and the design of our apparatus,the grit is below the depth of the Weir edge in the overflowing liquidbefore it reaches the Weir edge and therefore continues to settle intothe sump. Thus the supply of suitable surface reforming grains in thesump is continually replenished by this drain-back material, and iscontinually cleaned of unwanted material. The action just described isrelated to velocity of flow of liquid across the sump to the overflowedges and especially its velocity at the Weir edge.

We have found that eilicient reclaiming and re-use of grit in suchoperat1ons requires overflowing the liquid uniformly along a suilicientweir length to keep a uniformly shallow depth and low velocity of ow inthe escaping liquid, whereby to insure a positive separation of thesolid matter to be retained in the apparatus for re-use, but to carryolf the dirt.

An object of this invention, therefore, is to provide a rate body ofliquid will provide for washing off the dirt and settling back thegranular blasting material suitable for re-use. Because of the velocity`of liquid flow required for effective wet blast treatments, thisseparation requires an increase in the length of Weir edge beyond thatof a suitable sump or storage tank. It is an object of our invention toprovide this length without excessive increase in size and cost of theapparatus.

Another object of this invention is to condition the ow of excess liquidtoward a weir edge so as to favor sedimentation of the heavier mattersuspended therein.

Accordingly, we have set forth below an embodiment of our inventionwherein we achieve these objects by a novel Weir and advantageously witha novel baffle system each of which affords striking improvement andwhich through the novel bafde arrangement toward the Weir, undergoesabrupt changes in ow direction whereby the sedimentation of suspendedmatter therein is accelerated.

the suspended solids, a series of pocket-like extensions lare providedalong the Weir edge which both increase the effective weir length of thesystem yand provide quiescent 'mentation rate of the suspended matter ising `chamber 1 'ilakes, etc.

bodies of liquid adjacent these extended edges. These pocket-likeextensions may be in open communication with the body of liquid, but wend it advantageous to have baflles between to keep any rapid ilow awayfrom the weir edge, e.g., to allow liquid to enter into these extensionswell below the weir level and to fan out to the edges. disposed in thesame plane as the weir edges between them so as to be in effectcontinuous therewith, whereby the excess liquid overflows uniformly `andat a reduced rate along the effective Weir length. Accordingly, thesediincreased and also the velocity of the overflow liquid is uniformlyreduced along the effective weir length; and the efficiency ofreclaiming the grit is greatly increased.

In this specification land the accompanying drawings we have shown :anddescribed a preferred embodiment of the invention and certainmodifications and alternatives', it

will be understood, however, that these are given for purposes ofillustration in order that others skilled in this art may fullyunderstand the invention and the principles thereof and its applicationto practical ruse so that they can modify it `and adapt it in variousforms, each as may be best suited to the conditions of the particularuse.

In these drawings:

FIGURE l is a view in longitudinal vertical section taken on line 1-1 ofFIGURE 2;

FIGURE 2 is a view in horizontal section taken on Aline 2-2 of FIGURE l;

FIGURE 3 is a fragmentary isometric sectional view lof an apparatusembodying this invention;

FIGURE 4 is a detail view in section taken along the line 4--4 of FIGURE2; and

FIGURE 5 is a sectional view of one of the pocketlike extensions `inaccordance with this invention.

Referring to these drawings, the apparatus shown comprises a blastingchamber 1 and ilushdown or washing chamber 3 for deburring partstransported longitudinally therethrough by conveyor means, not shown. Inthe blastindicated in FIG. l such manufactured parts are treated forsurface rre-forming by the impingement thereon of surface-reforminggrains entrained in high velocity liquid streams. The ilushdown chamber3 is adapted for washing the part, :after such surface treatment, byhigh velocity, clear liquid streams to remove any residues from theblasting treatment, e.g., surface reforming grains, mold material, coresand, loosened scale or The present invention makes it feasible toreturn to the sump 5 the wash liquid and the grit thus 4washed `oif, andthus to reclaim the grit and to utilize the excess wash liquid to cleanthe reclaimed grit.

The parts to be thus treated are carried successively through theblasting chamber 1 and the ilushdown chamber 3. -For example, theindividual parts may suspend from lan endless chain conveyor extendingthrough these chambers.

A water-shed under the blast and wash chambers 1 and 3 comprises a sump5 which serves as a settling tank e.g., of rectangular shape, `and asloping gutter 7. The sump 5 is made of a number of plate members weldedat their edges, or otherwise joined, so as to converge downwardly inhopper-like fashion toward a number of blasting manifolds 9; yand thegutter 7 is likewise formed of plates joined at their edges to the edgesof sump 5.

The blasting manifolds 9 are affixed to a base plate 14 of sump 5. Pairsof inner plate members 1S are angularly positioned in the base of sump 5and joined to each other and to the slaping sides of the sump, e.g., bywelding abutting edges so as to complete 'hopper-like sections for eachof the blasting manifolds 9. The blasting manifolds 9 are disposedbeneath the blasting chamber and one end 16 of the water-shed extendsbeneath the ilushdown chamber 3.

Each manifold 9 Vis provided with several jet orifices or nozzles 19;and alined above these, respectively, are the The weir edges of thepocket-like extensions are blast tubes 20 which, combined `with thenozzles 19, constitute an eductor to suck in the settled slurry from thebottom of the sump and entrain it in the high velocity jet from nozzle19. The spacing between blast tube 20 and nozzle 19 is adjusted to givethe desired eductor action. The resulting blast is protected from theliquid in sump 5 by blast tube Ztl with any extension thereof, asdesired, such .as the casing 21. A liquid-conduit system, for supplyingclean liquid under pressure to the manifolds 9 is illustrated iat 22.This system comprises a pump 23 connected through the respectivemanifolds 9 with the blasting nozzles 19. The pump 23 ordinarily is ahigh pressure, high capacity pump and is immersed in a clear liquidstorage tank 25.

A second branch of the liquid conduit system 22 goes to the manifolds 9for the washing jets 29 in the flushdown chamber 3. These jets `aredirected against articles positioned in the path of the jet afterblasting with grit in chamber 1. The run-back from this wash falls intothe end portion of the sump where any grit yand heavier particles washedback gravitate toward and along yits sloping bottom. A rim 17 on sump 5and on pocket-like appendages 18 serves as an overflow `weil with itsextensive edge all at one level.

If enough peripheral space is provided in the sump to bring the liquidto a quiescent flow and allow the grit to settle out before it reachesthe vicinity of the weir 17, a simple Weir edge on the tank could besuillcient, but by the present invention, the area requirement for suchsettling is greatly reduced and efllciency increased.

In accordance with the principles of this invention, a baille structureis arranged about that portion yof the sump into which the drain-backmaterial is received. This baille structure, as shown, comprises aplurality of angularly related flat members 34, 35, 36, 37 and 38secured in the peripheral part of sump 5. The baffles 34, 35, 36, 37 and38 are alternately inclined so that each is directed toward, andsubstantially perpendicular to the pl-ane of, the nextoutwardly-adjacent baille. In addition, the upper edges of the bailles35 and 37 extend a little above the -weir level, while their lower edgesextend sufficiently below the Weir level to assure that the liquid levelbetween these bailles will overflow the upper edges `at a level abovethat of the weir. The effect of these bailles is that the liquid flowingoutwardly is forced to overflow the bailles 35 and, in doing so, tendsto deflect downwardly the grit particles, which have radial momentumtending to carry them outwardly as the liquid rises. Again at the baille36, both the liquid and any entrained particles tend to ilow up onto theramp surface of 36. The upper edge of 36 is formed as a lip to preventthe liquid from overflowing. As this liquid laps up on the ramp, liketidal water rising on a beach, it creates an undertow flowing back downthe ramp and this again gives a m0- menturn to entrained grit particles,which tends to throw it down onto the upper surface of the baille 3S,while the liquid again reverses Yits ilow and rises between baffles 36and 37. At 37 again, as `at 35, the radial momentum of any entrainedgrit particles carries them against the sloping underside of the bailleand thence downward, while the liquid overflows the top edge of thebaille 37 and eventually runs on over the weir edge 17.

The lower edges of the members 34 and 36, on the other hand, extend toIa lesser depth below the weir level and at an angle directed downwardlyinto the flow, thus functioning las a skimmer device to skim off anyfoam, and hold it in contact With the flowing liquid and give itopportunity to break and drop any grit which it has floated. Thesemultiple bailles at the surface of the liquid also smooth out any waveswhich might be formed by the blasting action and which, if notintercepted, might cause irregular overflow.

The -upper edges of the members 34 are juxtapositioned with, iand extendslightly above the level of, the lower edges 47 of the blasting chamber1 and, likewise, of ilushdown chamber 3. Thus, the inner rectangularbaffles 34, in eifect, form a pyramidal bottom section on the blastingohamber 1 and the ilushdown chamber 3, extending below the weir level.This allows room for the bailles 34- 37 with lesser overall dimensionsof the sump 5. The baflles 34 may, however, be outside the walls ofchambers 1 and 3, especially if the chamber Iwall is extended downwardso that its bottom edge 47a is below the liquid level in the sump. Thisis shown for example in FIGURE 4, in which the position of the bottom of47 in the other iigures is indicated by broken lines for comparison.

The baille 35 is spaced at its lower edge from the peripheral wall ofsump 5, leaving a narrow passage 49 which need only be large enough topass the normal ilow yof excess liquid and waste solids carried thereby.

The internal baille 38 positioned beneath the passage 49 gathers theliquid ilow to the outlet passage 49 and protects against a turbulentwashing of the sloping wall 6 onto which grit may have settled.

In the operation of the device shown and described above, the sump 5 isillled with a suitable blasting and washing liquid, for example, wateror an aqueous solution of surface treating chemicals, such asdetergents, rust inhibitors, passivating agents, defoamants and thelike. The grit, eg., malleable iron grit of the grade known in the tradeas G40, is dumped into the sump so that it settles into the bottom areasaround t-he jets 19. With the articles to be treated suitably supportedover the blast tubes Ztl-21, the pump 23 is operated to supply theliquid under relatively high pressure to the manifolds 9. This liquid,escaping through nozzles 19, entrains the grit by ejector action into ablast directed up through the blast tubes 20 into the chambers 1 andagainst the articles being treated. Likewise in chamber 3 a jet of theliquid is directed against the articles held above it, which havealready been treated by the grit blasting in chamber 1.

The liquid and grit fall back from this treatment into the sump 5,carrying with `it a certain amount of dirt, sand, scale, oil, etc.,removed from the surfaces of the articles being treated. As this fallback material includes excess liquid used in the ilush chamber 3, theremust be an `overflow equal to the excess. If this were merely yallowedto overilow the edge of a simple rectangular sump, the overflow`velocity would carry grit over the edge with the waste liquid withresulting nuisance in the disposal facilities and expense for replacingit with fresh frit. A larger sump reduces the velocity of the overilow,but such large sumps are expensive in themselves and `occupy expensiveplant area.

In the preferred embodiment illustrated this rate of ilow is attained byincreasing the length of weir edge by making a tortuous form as a resultof the numerous pocketlike extensions 18, each about a four inch square.Wider shallow pockets :can be used where less Weir length is requiredand narrow, longer and deeper pockets where greater length of weir isneeded. Sinuous weir edges can be provided instead of such rectangulartortuous form, or a meandering edge or saw-tooth form.

The liquid ilowing from the central area in the example shown, withinthe baille 34 toward the weir edge 17 must first pass under theinnermost baille 34 and also under the bottom edge 47a of the chamber 1,if it is arranged as shown in full lines in FIG. 4), then it spreadsradially and upward into the space beyond the baille 34 from which theliquid overflows the top of baille 35. Entrained grit, however, whichhas greater momentum in the radial direction, will tend to strike and bedeflected downward by the lower surface of the baille 35 meanwhilegradually settling through the liquid toward the bottom of the sump 5.

It will be noted that the liquid level as it overilows the baille 35 ishigher than the weir level, i.e., the reversal of ilow which occurs andthe very narrow gap at the bottom of baille 35 are suilicient to holdback the liquid until it reaches a substantial head.

Beyond the baille 35 the liquid again spreads out radially anddownwardly. Some of the entrained grit particles settle onto the topsurface of 35 and into the area between the bottom edge of 36 and thetop of 35. Another portion of the grit is carried up over the slopingface of baille 36 where it laps the surface yand turns back down tocreate an Iundertow, so that at the bottom of the baille 36 the liquidand entrained grit particles are flowing toward the baille 35. 'Dhus theentrained particles are again given a momentum causing them to traveldownward toward baille 35 and along its surface while the liquid againreverses its ilow to spread upwardly and outwardly in the area betweenbailles 36 and 37. Here again, as with baille 35, the outward momentumof entrained grit tends to carry it against the underside of baille 3'7,where it is deilected downwardly and settles toward the slot 49 at thebottom of baille 35, while the liquid overilows baille 37 and falls intothe final settling area between baille 37 and the Weir 17 and eventuallyoverflows into the trough 7. Here again the diversion from the ilow downalong the top surface of baille 37 to overflow the weir 17 causes anyremaining entrained grit to be carried by its momentum toward the slot53. The grit collects ilrst in the trough formed by baille 37 .and thenin the trough behind baille 37 and gradually settles through slots 53and 49 and along baille 33` and down into the sump.

In a preferred example as set forth, the lower edge of the baille 35 isls inch from the vertical peripheral wall of the sump and 1A inch fromthe top of the baille 38. In this instance, the baille 38 is about 30above the sloping bottom 6 of the sump 5 and about 20 downward slopefrom the horizontal. IBatlle 38 in this instance is about 3 wide, baille35 about 10" wide, baille 36 about 31/2" wide and baille 37 4about 2%wide. 34, 35, `36 and 37 Ialll slope at about 45.

The gap 49 is dimensioned to restrict the ilow therethrough so as toavoid washing upward from the gap. Thus, the outward ilow causes a smallrise in the liquid level at the upper edge of the baille 35 and likewisewith the baille 37. This results in a thin layer of the lightest liquid(i.e., that most free 'from the grit), overilowing the upper edges ofthese bailles. The intermediate bailles 35 and 36 force reversals in thedirection of ilow as described above so as to increase the separatingaction.

The grit used for surface-reforming is normally suspended in a liquid inthe sump 5. Due to the hopperlike configuration of the sump, the grainsof the grit gravitate toward an eductor device consi-sting of the jets19 land blast tubes 204.1, by which they are entrained in the highvelocity liquid streams emanating from the `nozzles 19 and blastedagainst the articles held above in chamber 1. The larger section 21 ofthe blast tubes serves to hold back the liquid i nthe sump and keep aspace for the blast to pass without interference. Liquid is directedunder pressure to each of nozzles 19 and 29 in jet-like fashion. (Theblast tubes 20-21 are omitted from FIG- URES l and 2 for clarity, ibutone shown in FIGURE 3.)

Accordingly, the grit impinges on the articles positioned in, or beingtransported through, the blasting chamber 1, with suiliciently highenergy to eilect the desired reforming process.

vDuring operation, solid mater suspended in the ilow- `back liquid iscontinuously settling out at a rate which is -a function of its size,density, and other characteristics. The sedimentation rate of thesuspended matter, however, is advantageously increased by ilowing theexcess liquid through the novel baille arrangement and thu-s subjectingit to abrupt changes in ilow direction which are transverse to itsnormal, lateral ilow pattern toward the weir edge 17. For example, onpassing beneath each of the members 34 and 36, the solid mattersuspended in the excess liquid is impelled downward below the Weir leveland, when the liquid has to ilow upward and over the members 35 and 37,the solids tend to continue downward due to their inertia added togravitational forces, so that they are well below the weir when theliquid, after the same lateral travel, approaches the Weir edge 17. Anysuspended grit which may pass the baffles 35 yand 36 is deflecteddownward by the member 37 and through the gap 49 between the member 35and the wall of sump 5.

During the reforming process, the `gnains of the grit are eventuallyworn down or shattered from the violent impacts and abrasion againsteach other and the parts being treated. According to this invention,however, a uniform reforming of the parts continues, because the surfacereforming grit, when worn down or shattered so far as to be no longersuitable for the reforming process is removed from the blasting liquid.

The articles after blasting in chamber 1 pass on through the ushdownchamber 3 where the surface of each part i-s washed clean by highvelocity streams of clear liquid directed through the nozzles 29 on theushdown manifolds 9.

Due to the breakwater action of the bafe arrangement, the overflowingliquid has been brought to a quiet uniform iiow condition so that itoverflows uniformly along the entire tortuous edge 17 of the weir. Theexcess liquid with the more readily suspended matter carried therebyafter passing over the weir edge 17 flows along the trough 7 to thesettling tank 25, from which a clear liquid overflows into the tank 24around the pump 23.

As already mentioned above, the depth and rate of flow of the excessliquid flowing ove1 the weir edge 17 is re- -duced by extending the Weiredge with a series of pocketlike extensions 18.

These are most economically made by notching or castellating t-he upperedge of sump 5, and welding onto the outside face and about each suchnotched position the triangular pocket structure 18. The Weir edges 17of the pocket-like extensions 18 are disposed in the same `plane as therest of the weir edge 17 and are continuous with those portions of theWeir edge 17 disposed therebetween. It is evident that, if desired, thepocket-like extension may be disposed yalong the inside face and aboutthe notched portions to secure the same result.

In order to provide for controlled flow into the pockets 18 (-see FIGURE5), a slot 56 is provided at the bottom .and the notch is left open atthe top, as shown at 57.

The wall 58 between may be a part of the originally Vformed sump tank 5,Which is merely sloted at 56 and the sump, and there settles towar-d andthrough the gaps 53 and 49.

Thus, it will be seen that the incorporation of the novel baie and Weirsystem of this invention with hydraulic classification system of theinstant type provides for a positive separation of the solids whichshould be retained, and with accurate gauging. Due to the smooth quietflow of the excess liquid to the weir edge 17 loss of grit due toturbulence is avoided. Moreover, as the effective weir length of theshed system can be varied by design of the pocket-like extensions 18,this action can be a-djusted to the requirements of different grits anddifferent input volumes of excess liquids.

We claim:

1. The method of hydraulic classification of reusable solid particlesfrom waste matter which comprises collecting a suspension in liquid ofsaid solid particles and waste matter in a zone of a predetermined size,settling said solid particles into the bottom of said zone from whichthey may be withdrawn for reuse quiescently overflowing excess liquidfrom said zone together with slower settling waste matter from amultitude of adjacent peripheral areas in a plurality of divergentdirections from each area over a linearly extended, substantiallyhorizontal, tortuously shaped, boun-dary occurring at the top outerperiphery of said zone, whereby a more effective skimming overflow fromsaid zonefis accomplished.

2. The method as defined in claim 1 which further comprises collectingsaid liquid suspension from above into said zone at a central areawithin said Weir edge, blocking the flow of all liquid, particles, andmaterial along the upper surface of said zone toward said weir edge fromsaid central area to cause it all to flow down into said zone for adistance whereby reusable particles are more readily separated from suchsurface flotsom.

3. The method as defined in claim 2 which further comprises while owingthe liquid from said central area to the edge of the zone, in shanplydiverting its direction ow from upward to downward slope and vice versaseveral times, whereby to accelerate settling of solids toward thebottom of said zone.

References Cited by the Examiner UNITED STATES PATENTS 1,333,287 3/1920White 209-155 1,512,561 10/1924 Oliphant 209-273 X 1,702,203 2/ 1929 Day51-8 2,200,587 5/ 1940 Tirrell 51-8 2,591,830 4/1952 Klepetko 209--208 X3,140,259 7/1964 Kelly 210-525 X I3,150,467 9/ 1964 -Umbricht et al51--8 FRANK W. LUTTER, Primary Examiner.

HARRY B. THORNTON, LESTER M. SWINGLE,

Examiners.

1. THE METHOD OF HYDRAULIC CLASSIFICATION OF REUSABLE SOLID PARTICLESFROM WASTE MATTER WHICH COMPRISES COLLECTING A SUSPENSION IN LIQUID OFSAID SOLID PARTICLES AND WASTE MATTER IN A ZONE OF A PREDETERMINED SIZE,SETTLING SAID SOLID PARTICLES INTO THE BOTTOM OF SAID ZONE FROM WHICHTHEY MAY BE WITHDRAWN FOR REUSE QUIESENTLY OVERFLOWING EXCESS LIQUIDSAID ZONE TOGETHER WITH SLOWER SETTLING WASTE MATTER FROM A MULTITUDE OFADJACENT PERIPHERAL AREAS IN A PLURALITY OF DIVERGENT DIRECTIONS FROMEACH AREA OVER A LINEARLY EXTENDED, SUBSTANTIALLY HORIZONTAL, TORTUOUSLYSHAPED, BOUNDARY OCCURRING AT THE TOP OUTER PERIPHERY OF SAID ZONE,WHEREBY A MORE EFFECTIVE SKIMMING OVERFLOW FROM SAID ZONE ISACCOMPLISHED.